To help the former Man Utd boss through unemployment, here's a handy guide to global cabs

Distinguishing featuresOverwhelming greenness. Traditionally, Mexico City's taxis were painted yellow, but in the early Nineties officials decided they should all be painted green "to give the impression of ecological transport..."

Driving styleIf you've got an official one, not bad. If you're in a ‘pirata' taxi, probably really quite scary.

DriverAgain, if you're in an official cab, courteous. If not, likely armed and dangerous.

PerformanceSlow and smoky. The ‘ecological' upgrades stretched no further than a coat of green paint, so we're talking an ancient air-cooled engine and Fifties tech. But, hey, at least they were built just round the corner in Puebla...

Risk of deathHigh. Official advice is that you should never hail a cab off the street, and you should always check for the official taxi- cab license plate.